


Demon Hunter (RWBY x Demon Slayer)

by TheFoolXXII_Max_X



Category: RWBY, 鬼滅の刃 | Demon Slayer: Kimetsu no Yaiba (Anime)
Genre: Alternate Universe - Fusion, Family Feels, Gen, Random - Freeform, practice
Language: English
Status: Completed
Published: 2019-11-23
Updated: 2019-11-23
Packaged: 2021-02-26 07:20:36
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 3,265
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21529699
Author URL: https://archiveofourown.org/users/TheFoolXXII_Max_X/pseuds/TheFoolXXII_Max_X
Summary: Inspired by episode 19 of Demon Slayer. The return of RWBY and my simultaneous watching of Demon Slayer caused me to come up with this idea.Yang and Ruby fight the powerful spider demon on the mountain. Things get harder when a loved one is placed in serious danger.
Relationships: Qrow Branwen & Ruby Rose, Qrow Branwen & Yang Xiao Long, Ruby Rose & Yang Xiao Long
Comments: 3
Kudos: 18





	Demon Hunter (RWBY x Demon Slayer)

Yang couldn’t believe it. Her Nichirin Blade had been broken. The yellow sword had just snapped clean in two when she tried to cut the thread the spider demon girl had sent at her. She had been able to dodge but ended up getting a cut across her face. Ruby ran to her side, concern easily seen on her face despite her ever-present bamboo gag.

“I’m fine, Ruby. I’m fine,” she reassured her sister as she got to her feet. “Don’t try to slice the threads. We need to at least keep one sword.”

Ruby glanced at her red-silver edged sword and nodded. 

Yang glared at the spider girl and her supposed-older sister. _If her threads could break my sword, does that mean their even tougher than the demon’s body I couldn’t slash?_

She thought back to the large spider demon she had been forced to leave Blake with. Her grip on her broken sword tightened. She had to end this fight quickly and get back to the cat-masked girl. Hopefully, someone strong had come to her friend’s aid. Maybe Weiss. Or Jaune, Ren, or Nora. Or even her mom.

_Mom_

It had been a shock to see her mother on the mountain. This was honestly the last place she had expected to see Raven. Though she had been more shocked by the similar wooden box the woman had on her back and how the scent it gave off was similar to Ruby’s.

Yang snapped out of her thoughts just in time to dodge the threads sent at her. _Now’s not the time to be thinking about that!_

She pushed off the ground and headed straight for the demon. _If I can’t slash the threads, I’ll go directly for her neck!_

“Ruby! Go for her directly!” Her sister nodded and followed her lead.

The demon was not phased and merely summoned more threads at the sisters. They dodged and weaved as the strings carved the ground around them. Even with Ruby’s demonic speed, they were kept at bay.

“So you still refuse to take back what you said about my family bonds?” the demon questioned.

Yang glared defiantly at her enemy.

“Fine. I’ll just cut you to pieces.”

With a tug of her wrist, large webs of thread came rush at Yang and Ruby. _I can’t dodge them!_

“Ruby!” the blonde cried out as she reached for her little sister who did the same for her.

Only the threads never touched them. All were shocked when someone else took the hit. A man had run out from the surrounding woods and shielded the girls, the threads slashing him and spraying his blood.

“Uncle Qrow!”

The two girls caught their uncle before he could fully collapse and quickly ran him to cover. “Uncle Qrow, hang in there!” Blood seeped into his ruined white kimono and he hissed in pain.

The spider demons were stunned. “That man ran out to protect them. But he has the aura of a demon, like that red-haired girl,” the older sister observed. When she noticed her companion had not responded, she looked over to see her trembling.

“Hey…, is… that man…” She pointed a shaking finger. “Part of your family?”

“So what if he is?!” Yang angrily snapped. Her and Ruby’s focus was on their uncle. The blonde held Qrow’s arm together. 

_The wound’s so deep. His left wrist is practically falling off! Come on! Heal! Heal!_

The spider girl remained dumbly standing. “Family… family… The uncle has been turned into a demon. Yet he still protects them.”

“E-Emerald?” the other demon nervously called out but was ignored.

“An uncle protecting his nieces. Risking his life. That’s a genuine family bond! I want it!” Emerald exclaimed.

“W-! H-Hey, wait! Please, I’m your older sister! Don’t abandon me!”

“Shut up!” Emerald unleashed an attack that easily sliced her sister into segments and destroyed much of the forest behind her. “None of you ever properly fulfilled your roles. Not even once,” she coldly said.

The other demon fearfully looked up at her. “H-Hold on. I was the older sister you wanted, right? Please let me redeem myself!” she begged.

“Fine, go kill the hunters still on the mountain.” She turned away from her. “Do that, and I’ll overlook what just happened.” Her sister picked up her head and ran off to fulfill the order.

Yang watched the scene while Ruby comforted Qrow.

“Girl. Come out and let’s just talk.” 

Yang remained behind their cover. _Just talk? What is she saying?_ She reached for her sword but stopped when her uncle suddenly grabbed her hand. He was still breathing heavily from his injuries but he leaned in and whispered to her in a raspy voice.

“One… Twelve Grimm… here.”

She stared at her uncle in shock. One of Salem’s Twelve Grimm was here!? She anxiously glanced up. Could it be…?

The spider demon spoke again. “To be honest, I was quite touched. Seeing that bond you share actually gave me the chills. I can’t even describe how moved I was with words.” She looked up at Yang. “Unfortunately, the two of you will only die here. That would be a shame, wouldn’t it?” Ruby glared at the other demon as she comfortingly held onto Qrow, who had finally managed to heal from all his wounds.

“But, there is a way you can avoid that.” Emerald held out her hand. “Give your uncle to me, and I’ll let you two live.”

Yang and Ruby stared at their opponent. “What are you even saying!?” exclaimed the blonde.

“It’s simple. Your uncle will become my uncle from here now.”

“Do you actually think we would agree to that!” Yang shouted. “And Uncle Qrow isn’t a thing! He’s got his own thoughts and feelings, and he’d never be an uncle to you!”

Emerald didn’t waver. “It’s fine. I’m stronger than you. So I will create a bond of terror between us. I’ll make sure he learns what happens if he goes against me.”

Yang’s temper reached its end. She grabbed and raised her broken blade at the demon. “I’ve had enough of the garbage you’re spewing! Using fear to keep someone in line is not the bond of family! Someone as twisted as you could never understand!”

Emerald’s frown deepened.

Yang threw Ruby’s box aside and the sisters walked out together to confront their enemy.

“We’ll never hand him over to you,” Yang declared.

Emerald stared at them. “Oh well. I’ll just kill you two and take him.”

“We’ll cut your head off first.” Yang gripped her broken sword while Ruby raised her’s.

A cruel smile sprouted on Emerald’s face. “That’s a powerful boast.” She placed her hand over her eye and brushed it away. “Let’s see if you can even stand a chance against me.”

Now her eye showed an engravement.

**Upper Six**

Yang tightened her grip. _Upper Six… So she is one of the Twelve Grimm! We still have Ruby’s sword… but what can I do with mine?_

“You both have a look in your eyes. You two really think you beat me?” Emerald exclaimed as she summoned her threads. The sisters heard a rustling and looked up to see Qrow being pulled out of cover towards the other demon.

“No, Uncle Qrow!”

Emerald gripped the man around his throat. She pinned his arms to himself with thread so he couldn’t fight back. He growled angrily at her. 

“Now I have him. Don’t you see this fight it pointless?”

“Get your hands off him!” Yang and Ruby rushed forward. Qrow growled and managed to free one of his hands, albeit cutting it up. He raked his black claws across his captor’s face. Emerald didn’t flinch and just threw more threads at his nieces. They were able to quickly stop and flip backward to dodge but when they regained their footing both noticed something wrong.

“Where’s Qrow?”

Then blood fell between the sisters. They looked up and stared in horror.

“Uncle Qrow!”

He was strung up, upside, with the threads easily cutting through his clothes and into his skin. Several threads had formed a gag, cutting into his mouth. Qrow grunted in pain and in vainly tried to reach for his sword, but all that did was cause the threads to cut deeper into his arm.

"Quit being hysterical,” Emerald said as the slashes in her face healed. “It’s not like that will kill him. He is a demon. But it seems I have to teach him a lesson. So I’ll let him bleed for a while. And if he still hasn’t learned, then I’ll just leave him up there to roast for a bit at sunrise.” 

“Let go… of Uncle Qrow!” Yang shouted. She readied her weapon and rushed at her enemy. Emerald sent out her spider threads that easily hit the hot-tempered blonde. Yang gasped and fell. She heard footsteps approach and looked up just in time for Emerald to kick her in the jaw. She was sent flying up and back into a bush. She spat out blood pooling in her mouth. Emerald immediately dodged a slash from behind. Ruby, enraged at seeing her family hurt, slashed quickly at the other demon. Each time though the other girl managed to evade her blade. A strong backhand to the face snapped the band of her gag, causing it to fall out. Ruby spat out the blood and readied herself again.

Emerald looked annoyed. “You’re still going to try, even though you can even touch my neck.” Ruby gave a low growl, her fangs bared. The spider demon walked towards her. “Alright then. Try and hit me.” The other demon spread her arm out, leaving her wide open. Ruby’s silver-and-red eyes narrowed and she took a swipe at her opponent only to be dodged and backhanded again. This time she spun around and was able to aim her sword at her enemy’s neck.

The sound was like metal against metal. Both Yang and Ruby stared in shock. “Ruby’s sword… won’t even go through!”

“I told you, you both can’t beat me.”

Threads whipped out and slashed into Ruby. Her sword arm was severed and she gasped out in pain.

“Ruby!” Yang rushed out to aid her sister, Emerald just grabbed her outstretched wrist and kicked her into Ruby, sending both girls crashing into a tree.

Qrow let out muffled yells and began struggling even more against the threads upon seeing his nieces beaten up.

“Yaaan!! Ruubee!!”

His struggles were starting to get on Emerald’s nerves. “That’s enough. Quiet down.”

With a clench of her hand, the threads tightened and wrenched Qrow violently. More blood sprayed from his wounds and he let out a muffled scream of pain.

“Stop!” Yang yelled.

Emerald paid the blonde no mind and just stared up at her captive. “I’m your niece now. Stop your whining.”

Yang felt her temper flare up but pushed it down. _Calm down! Don’t run in head first!_ She glanced over her shoulder. Ruby was unconscious and her arm had not grown back. The stump was still bleeding. Qrow was soon overcome with pain and fell unconscious in the threads.

_You need to concentrate! Focus your breathing and release the final Form!_

Yang sucked in a deep breath of air. She felt it flow through her body, strengthening her tired muscles and calming her screaming mind. 

**_Total Concentration!_ **

She pushed forward, golden flames arching from her sword. Emerald sent out more threads, but this time, Yang was able to strike them away, much to the demon’s surprise.

**_Breath of the Sun Dragon! Tenth Style! Dragon of Sunshine!_ **

The flames of her blade congregated into a long golden dragon that roared as it followed and bite through the threads with her sword.

_It worked! I was able to cut through!_

Emerald for the first time in this fight was growing concerned. _With each rotation, that attack grows stronger. This could be a problem._

Yang continued running forward. _I can do this! I just have to get in close! I can beat her!_ She batted more and more threads away, the sun dragon still going strong.

The tips of Emerald’s fingers reddened as did the threads attached to them. “Did you really think this was how strong these threads could be?”

**_Blood Grimm Art: Slicing Respite Cage_ **

_What?_ Yang couldn’t see that Ruby had woken up and was watching in horror as the red threads closed in on her sister.

_These threads… they give off an entirely new scent! I don’t have enough energy to cut through them! But I can’t die here! Qrow! Ruby! They need me! I can’t-!_

Ruby cried out and reached towards her sister. Time then seemed to slow as memories of a past life came to her. Foggy at first but soon they cleared.

* * *

_A young Ruby and Yang laughed as they played, spinning around with small sticks. They were mimicking their parents’ and uncle’s use of a blade. A woman sat in the house, smiling as she watched them._

**_Mother_ **

_“Ruby. Remember to breathe. Once you have it under control, you’ll be able to be like the roses.”_

**_Roses…?_ **

_Her mother gently ran her fingers through her daughter’s hair. “When you learn the correct way to breathe, you’ll be just like the roses. Beautiful and red, but dangerous enough to protect those around you. Remember, be like the roses.”_

* * *

Ruby snatched up her sword in her only arm and dashed towards her sister. She drew breath, quickly and deeply.

**_Breath of the Roses: I, Scatter!_ **

A flurry of rose petals sprung from Ruby’s sword as she easily sliced through the threads surrounding her sister. But she wasn’t done yet. She swung her missing arm stump at Emerald, spreading blood into the air.

**_Blood Grimm Art: Red Like Roses!_ **

Her blood shifted into a cloud of petals that were like a million miniature swords. They followed Yang as she rushed forward, blocking thread after thread, causing the amount to wane as time went on.

Ruby collapsed. Those two consecutive attacks had taken everything out of her. But it was enough.

Yang determined more than ever kept on going despite the nicks she received here and there. 

_Keep running! If you stop now, you’ll collapse from the strain of keeping Total Concentration up for so long! And Ruby’s actions will have been for nothing! Qrow will be taken! So keep going! You have to protect them!_

The blonde let out a determined yell as she rushed at Emerald, her sister’s rose petals slicing away any threads that came near her. Finally, the demon realized she could actually be in danger and quickly retreated away. But no matter how far or how many times she jumped back, Yang was right on her, swing away as the petals danced around her.

Finally, Yang saw it; the opening thread. 

Emerald threw out more threads that took out the last of Ruby’s petals. At the same time, Yang swung her sword forward, the golden dragon as bright as ever. 

_This is it! Take her out! Even it means getting slashed at the same time!_

* * *

“Qrow! Qrow! You have to wake up!”

The sleeping demon vaguely recognized the voice calling out to him.

_Tai…?_

“Please, Qrow. You have to save Ruby and Yang. I know you can do it,” the blonde man said.

His brother’s eyes remained closed.

“Please hurry Qrow! Ruby and Yang will be killed, too!”

That last sentence definitely woke him up. His mismatched red eyes snapped open and he outstretched his hand, willing power into his blood.

**_Blood Grimm Art: Crow Claw Scythe!_ **

With a clench of his hand, Qrow’s blood spiraled up and formed a crow made entirely from it. With a cry, it flew at his enemy for slashing its talons forward, sending arcs of wind at the spider demon. The arcs easily sliced through the threads, giving Yang a complete opening. She passed through the wind, but it didn’t cut her at all. It just felt like a cool night breeze.

Yang’s broken sword connected with Emerald’s neck. A mixture of some of her sister’s and uncle’s blood spread out and coated it, strengthening the metal just for this. 

“The bond between me and them… can never be severed!” Yang declared as she sliced through the demon’s neck. A ring of golden flames surrounded them and Emerald’s head flew off, trailing rose petals and black feathers. It fell several feet back and both her body and Yang collapsed. The threads holding Qrow loosened and he fell to the ground unmoving. Ruby remained laying on the ground, her arm still missing.

“Ruby! Uncle… Qrow!” Yang weakly called out. She breathed heavily. “We did it. All of us.”

_Ruby and Uncle Qrow saved me. Dad was able to teach me the final form. Summer taught Ruby the Breathing Style of the Roses. We won._

Yang struggled to crawl towards her family. _My body can barely move. I kept Total Concentration up too long._ She stabbed her broken blade into the ground to help her crawl. _I have to get up! I need to get to Blake!_

Suddenly, she froze as a strong scent wafted from behind her. _What is this? The scent of blood… has grown stronger! Come to think of it, I didn’t smell the ash that follows a demon’s death. That means…_

She heard footsteps approaching her. “But I cut off her head. How is she still alive?”

“You really thought you beat me?” asked an angry voice. “You idiot. I cut my own head off with my threads before you could,” Emerald explained. Yang still tried to crawl away, to get to her sister and uncle to protect them. “You’ve really irritated me. So I’m just going to kill all three of you,” the demon said as she placed her head back on. She readied her blood threads. “I think I’ll actually enjoy that,” she growled.

_Come on! Get up! Get up! Find the right breathing technique! Get up now!_

**_Blood Grimm Art: Murderous Thief Basket!_ **

Yang watched the threads form around her. _Don’t panic! Control your breathing!_ Her arm twitched but didn’t listen to her command to move. _I… can’t raise my sword!_

The threads closed in and she felt them cut into her. _No… it… can’t end… here!_

Something leaped over her and then the threads fell to harmless pieces around the blonde.

_Who was that? Mom?_

“You… did good… firecracker. Leave this… to me.”

Yang glanced back and saw her uncle standing with his black Nichirin blade drawn. He glared at the other demon. Emerald’s frustration was boiling over. “All of you are getting in my way!”

**_Blood Grimm Art: Slicing Respite Rotation!_ **

Qrow had to end this quickly. He barely had enough energy to stand.

**_Total Concentration_ **

He closed his eyes and drew in a deep breath. He let it flow through him. Wind spiraled from him.

**_Breath of the Wings… Tenth Style… Albatross of the Storm_ **

The threads passed over him and fell to pieces. The current of wind dissipated as he lowered his blade, black feathers falling to the ground.

Emerald blinked. _What just happened? When did he move his sword? He easily cut down my attack?_ The demon growled. “That’s not possible!” She readied her attack again. “Just one more time!”

She blinked and then Qrow was right next to her, his sword easily slicing through her neck. Emerald’s face remained stunned as her head fell and Qrow flicked her blood off his sword.

“You… couldn’t beat… a Pillar,” he said to his defeated opponent.

**Author's Note:**

> So this is just something I wrote for fun because I couldn't get the scene out of my head and just had to write it down. It was pretty fun coming up with names for the attacks and Breathing Styles.
> 
> So some background:
> 
> -Yang and Ruby are Tanjiro and Nezuko. Tai and Summer were unfortunately killed by Salem, who is Muzan Kibutsuji in this AU. They were retired Pillars of their self-invented Breathing Styles. 
> 
> -Qrow is the Wing Pillar and co-founder of the Breath of the Wings. The other was his sister Raven, a renegade Demon Hunter and her blade is red.
> 
> -When Yang came back to see her parents dead and her sister injured, Qrow was gone. She first thought he was completely devoured, then got the horrible thought that maybe he had turned into a demon and was responsible. What happened was Raven came the night before for her monthly visit and found the carnage. She found Qrow barely alive and couldn't find a pulse on Ruby, so she thought she was dead. She planned on coming back to bury them after she got Qrow medical help, but he ended up turning into a demon.
> 
> -The reason Raven didn't kill Qrow was that he was able to remember her and didn't attack her. He instead saved her from other demons.
> 
> -Qrow can talk but his throat was damaged from the claw slash by Salem meant to kill him. His left eye was also damaged so it regenerated to have a more demonic appearance.
> 
> -Yang and Ruby follow Tanjiro and Nezuko's journey.
> 
> -Blake is Inosuke's equivalent. She wears a kabuki cat mask. Her blade is dark purple, and she uses the Breath of the Shadows.
> 
> -Weiss has no Demon Slayer equivalent. Her blade is white, and she uses the Breath of Ice; the same as her sister who is a Pillar.
> 
> -Jaune is Zenitsu's equivalent. He and Nora both use the Breath of Thunder though she is better. His blade has a golden lightning design and her blade is pink.
> 
> -Ren's two blades are green and he uses the Breath of the Lotus.
> 
> -Pyrrha has unfortunately died before the story. She was killed by the Upper Grimm Cinder. Her blade was red and she used the Breath of the Flames.
> 
> -The Upper Grimms in no particular order is Mercury, Cinder, Emerald, Hazel, Tyrian, Neo/Roman. After some deaths, Watts and Adam join the ranks.
> 
> -The Pillars are Ozpin and his allies.
> 
> -The demon designs of Ruby and Qrow are as follow:
> 
> Ruby: Bright red streaks growing from the roots of her hair, pupils now bright red, bamboo gag, fangs, and pink claws.
> 
> Qrow: Paler skin, bangs fade to very pale pink, right eye dark crimson; left eye pale blue with dark crimson sclera, left eyelashes very pale pink, fangs, and black claws.


End file.
